causes the body to need increasingly larger amounts of the
drug to get the same effect that was originally produced.

Explanation:

Drugs have different effects depending on the drug itself, the person taking it and their surroundings. Learn how your body processes drugs and about the short-term and long-term effects. Taking drugs can affect not just your physical and mental health, but your whole life. Just one pill can kill.

Mainly, the number of genes that control traits.

Explanation:

Polygenic inheritance does not follow Mendel's law of dominance. According to Mendel the dominant trait will mask the recessive trait however, this is not always the case. Polygenic inheritance states that traits are controlled by two or more genes and is also dependent on the environment.

Let's take skin color for example. A fair-skinned person will have a child with a dark-skinned person.

Mendelian inheritance would assume that the offspring would either be fair or dark only.

Polygenic inheritance would assume that the offspring would be either fair, dark, or a tone in between, depending on the environment they are in as well.

Hope you understood it.